Antenna structure



Sept. 19, 1961 J. R. WINEGARD ANTENNA STRUCTURE 2 Sheets-Sheet 1 Filed April 20, 1960 P 1951 .1. R. WINEGARD 3,001,195

ANTENNA STRUCTURE Filed April 20, 1960 2 Sheets-Sheet 2 IN VEN TOR.

2 M'daw United States Patent Iowa Filed Apr. 20, 1960, Ser. No. 23,488 7 Claims. (Cl. 343864) The present invention relates to an antenna structure having matching stubs which not only enable the obtaining of an impedance match between the antenna and the lead-in but also facilitate the installation of the antenna.

With antennas which are to be used for high frequency, very high frequency and ultra high frequency radio waves, such as for example those utilized in frequency modulation and television transmission, it is particularly important that the impedance of the transmission line match the impedance of the antenna. For most installations of television antennas a 300 ohm transmission line is employed.

,Such a transmission line is relatively inexpensive and is easy to install between the antenna and the receiver.

Where the only element, or the driven element, is a dipole, it is not particularly dithcult to obtain a reasonably accurate match in impedances between the 300 ohm line and the dipole. Folded dipoles, which are more commonly used, in theory have an impedance of slightly less than 300 ohms and actually are somewhat below this in the usual instance. In high signal strength areas the impedance mismatch normally is not too troublesome. However, in fringe areas the matter of a proper match between the folded dipole and the antenna lead-in becomes more significant. Furthermore, in antennas for fringe areas it is common to use a plurality of parasitic elements on the antenna in addition to the driven element to improve the strength of the signal from the antenna and the direotivity of the antenna. The useof these parasitic elements substantially lowers the antenna impedance. The extent to which it is lowered will depend upon the number and positioning of the parasitic elements with respect to the driven element. With many antennas designed for fringe area operation the impedance will be well below 300 ohms. Thus there is a problem of obtaining a proper match between the antenna and the transmission line. Various systems have been devised for obtaining a match including the use of open quarter wave matching stubs.

For fringe area reception it is quite common to use a series of stacked antennas. Thus two or more antennas are positioned one above the other on a single mast and connected together to feed the transmission line. When this practice is followed the impedance matching problems again are encountered. Generally speaking it is desirable to connect the electrical transmission line midway between the two or more antennas and in such case the total impedance of the antenna system as seen by the transmission line is a fraction of the impedance of any one antenna. For example, with .two antennas in the system with the transmission line being connected midway between the two antennas the impedance of the antenna system as seen at the point of connection of the transmission line is one-half of the impedance of each individual antenna.

The principal object of my invention is to provide an antenna structure which incorporates impedance matching elements to provide a suitable 300 ohm impedance connection for attaching a 300 ohm line to a single antenna and which can be used in stacking two similar antennas to provide a 300 ohm connection for the transmission line midway between the two stacked antennas. One advantage of the structure I have devised is that while a connection is provided at 300 ohms to match the commonly used 300 ohm transmission lines to a single ani 3,001,195 Patented Sept. 19, 1961 tenna this connection may be varied to give an impedance as seen at the transmission line connection of anything between the actual impedace of the driven element, say to ohms, up to 600 ohms. Thus, in those special instances where it is desired to use such an antenna with for example a 450 or 600 ohm transmission line the antenna connections may be quickly adjusted to provide an impedance of the desired value as seen at the transmission line connections.

Further objects and advantages of my invention include: the impedance matching structure is easy and simple to construct and inexpensive to add to any one of the various types of commonly used receiving antennas; the structure may be used with any one of the numerable variations that exist in receiving antennas, e.g. variations in number and positioning of parasitic elements, etc., and still provide a proper 300 ohm match for the connection of the transmission line; the device not only provides a 300 ohm connection for a pair of stacked antennas but also acts as a stacking harness and facilitates the installation of a pair of stacked antennas.

Additional objects and advantages will become apparent from the following decription taken in conjunction with the drawings in which:

FIGURE 1 is a perspective view of a pair of antennas embodying my invention stacked and harnessed together to feed a single transmission line;

FIGURE 2 illustrates one of the antennas of FIGURE 1 used alone on a mast to feed the transmission line;

FIGURE 3 is an enlarged bottom view of the impedance matching structure;

FIGURE 4 is a partial elevational view partially in section, showing the structure of FIGURE 3; and

FIGURE 5 is an enlarged section as seen at 5-5 of FIGURE 4.

Referring to FIGURE 2 there is illustrated an antenna generally 10 affixed to a mast 11 by a clamp generally 12. FIGURE 1 illustrates two identical antennas 10 and 10' secured to a mast 11 by clamps 12 and 12 respectively.

Each of the antennas 10 includes a metal boom 14 on which are five metal parasitic elements and a driven element. The five parasitic elements are directors 15, 16 and 17 and the reflectors are 1 8 and 19. The driven element in the illustrated embodiment is a folded dipole generally 20. In the illustrated embodiment each of the elements 15-20 is made so that it may be folded generally parallel to boom 14 to facilitate packing and shipping of the antenna. However, this feature is not a significant part of the present invention. As is the conventional practice, boom 14 and parasitic elements 15-19 are all conductors and are electrically connected together.

The structure and mounting of the dipole 20 is best seen in FIGURES 2-4. It includes a pair of elongated,

generally U-shaped, members 22 and 23 which are atnection between the top ends of members 22 and 23 and boom 14.

Below and attached to saddle 24 is an insulator 30. The lower ends of members 22. and 23 are spaced along the length of insulator 30 and secured to the insulator by bottom straps 29 and rivets 31. Attached to the upper ends of rivets 31 are a pair of generally horizontal posts 32 and 33. Posts 33 are positioned in a generally horizontal plane slightly below boom 14. Post 32 lies generally in a plane parallel to and at one side of mast 14-. Similarly, post 33 lies in a plane generally parallel to and at the opposite side of boom 14. Rivets 34 pass through posts 32 and 33 adjacent the outstanding ends thereof. Bars 35 and 36 are attached to posts 32 and 33 respectively by rivets 34. Each of bars 35 and 35 are made from tubing flattened at the ends. The extending ends are provided with openings 37 through which connecting bolts are inserted when two of the antenna units are stacked as hereinafter described.

Intermediate the ends of bars 35 and 36 is in insulator 4-0 which extends between the bars. Bolts 41 pass through bosses at the opposite ends of insulator 4t; and are held in place by wing nuts 42. L shaped members 43 under the heads of bolts 41 clamp the members 35 and 36 against insulator 40 and provide an electrical connection from the bars 35 and 36 to bolts 41. Intermediate the ends of insulator 4! is a recess 44 (best seen in FIGURES 4 and 5 to receive the U shaped portion 45 of a spring clip 46. :Clip 46 is attached to boom 14 by a rivet 47.

The posts 32 and 33 and the bars 35 and 36 connected thereto are essentially a linear one-quarter wave matching transformer. The principles of such transformers are well known in the art and from the available knowledge one skilled in the art can readily develop the particular size and spacing of components for a specific antenna. See for example pages 1031()7 and 165168 of The A.R.R.L. Antenna Book of the American Radio Relay League, Inc. (1954), the disclosure of which book is incorporated herein by reference. My invention resides in the structure of such a transformer which not only facilitates the installation and the obtaining of the proper impedance match with a single antenna, but also does the same thing when two such antennas are to be stacked.

Since, in by far the majority of cases the antennas sold will be for installations where a 300 ohm dual lead-in is used, the insulator 40 will be clamped into place on bars 35 and 36 in a position such that L members 43 contact the bars at a point such that when the clip is engaged with insulator it) as illustrated in FIGURES 35 the insulator will be in the proper position along bars 35 and 36 to provide the desired 300 ohm connection.

When the user or installer receives the antenna it will of course first be unpacked. Usually, to facilitate the packing, elements 15-20 are folded generally parallel to boom 14- so that the first step will be to unfold the elements. The boom 14 then will be secured to mast 11 by clamp 12 and the dual wire lead-in Sil will be connected to the bolts 41 by wing nuts 42. One of the wires 55a will be connected to one of the bolts 41 and the other Wire 5512 will be connected to the other bolt 4%. The lead in 50 then will be run to the receiver and may be supported by suitable stand-01f insulators 51. The exact sequence of the steps of erecting mast 1%, connecting lead-in 50 and fastening boom 14 to mast 11 will depend upon the preferences of the particular installer. In any event it is an extremely simple operation for the installer to erect the antenna 15 and to connect the leadin 50 thereto in a manner such that a proper match is obtained between the 300 ohm lead-in 5t) and the impedance of antenna 10.

In an extremely few instances an individual may wish to use a lead-in having an impedance different than 300 ohms, say for example 450 ohms. In that instance the wing nuts 42. are loosened and the insulator 40 disengaged from spring clip 46. The insulator is then moved longitudinally of bars 35 and 36 until 5.. members 43 contact the bars at a point such that the desired impedance will appear at the terminals provided by bolts 41. If for example 450 ohms is the desired impedance, insulator 49 will be moved toward the ends (as represented by openings 37) of bars 35 and 36. The impedance at the open end of the bars will be approximately 600 ohms. When the desired position of insulator 4b is determined, the insulator is clamped in place by bolts 41 and a suitable support provided between boom 14 and insulator 40. A support may be fabricated by a number of turns of electricians tape between the insulator and the boom.

If two stacked antennas are to be installed, as illustrated in FIGURE 1, the top antenna 10 is secured to mast 11 and insulator 40 is disengaged from clip 46 to permit the insulator and bars to swing downwardly about rivets 34 as illustrated in dotted lines in FIGURE 4. On the bottom antenna both of wing nuts 42 are loosened and one of them is removed so that the insulator may be swung about the other of the bars 35 or 36. The insulator 40 is then disengaged from the clip 46; the insulator swung about the bar to which it is loosely connected so as to clear boom 14'; and both of bars 35 and 36' are swung upwardly over boom 14. The insulator 40 is then reconnected to both of the bars and wing nuts 42 tightened in place on bolts 41'. Antenna 10' is then fastened on mast 11, aligned directly under antenna 10 with the openings 37 in bars 35 and 36 aligned vertically with the openings 37' in bars 35 and 36'. Bolts 53 are then inserted through openings 37 and 37 in each pair of bars to connect the respective pairs of bars to each other and to the wires 50a and 50b of lead-in 50. Since the impedance seen at the ends of bars 35 and 36 which ends are represented by openings 37 is 600 ohms the combined impedance when two antennas are connected as illustrated in FIGURE 1 will be 300 ohms as seen by the lead-in 50 connected to bolts 53.

The antenna construction herein described is suitable for antennas intended for reception of one TV channel, several closely spaced channels, and for all channel antennas. The antenna of FIGURES l and 2, for example, is especially suitable for reception of TV channel 13. In an actual construction, the following approximate dimensions were used:

Arms 32-35 %1' (1%, spaced 2 15" overall eng Length of arm 32--.." 234()center of element 20 to rivet Length of arm as--- 12 4' (rivet 34 to hole 37).

D1pole20 Each arm 26 (before jolding) with rivets 31 spaced 3 4 long, 10" in front of element 20.

Director 1L 2 Director 16"... 23 long, 20%" in front of element 20. Director 15 23 long, 32%" in front of ele-' ment 20. Reflector 18 275/ long, 14%" behind element Reflector 19 27 3f long, 19 ,4 behind element Boom 14 1 diameter.

The foregoing description of a specific embodiment is for the purpose of complying with 35 USC 112 and should not be construed as imposing unnecessary limitations upon the appended claims inasmuch as modifications and variations thereof will be apparent of those skilled in the art, and such modifications and variations are deemed to be within the scope of my invention to the extent that they are not excluded by the limitations of the claims.

I claim:

1. In an antenna including a mast member, a boom member, a driven element and a parasitic element, the improvement comprising: a pair of fixed, spaced, connector posts attached to said boom and electrically connected to said driven element; a pair of elongated relatively rigid bars, each bar being secured to a post respectively for pivotal movement about a generally horizontal axis; and insulator means connected to each of said bars to releasably support said bars from one of said members.

2. In an antenna including a mast member, a boom member, a driven element and a parasitic element, the improvement comprising: a pair of fixed, spaced, connector posts attached to said boom and electrically connected to said driven element; a pair of elongated relatively rigid bars, each bar being secured to a post respectively for pivotal movement about a generally horizontal axis; an insulator interconnecting said bars and positioning said bars in a generally parallel relationship; and means to support said bars from one of said members.

3. In an antenna including a mast member, a boom member, a driven element and a parasitic element, the improvement comprising: a pair of fixed, spaced, connector posts attached to said boom and electrically connected to said driven element; a pair of elongated relatively rigid bars, each bar being secured to a post respectively for pivotal movement about a generally horizontal axis; an insulator extending between said bars; means releasably connecting said insulator to said bars and positioning said bars generally parallel to each other; and a clip releasably aflixing said insulator to one of said members.

4. In an antenna including a boom member, a driven element and a parasitic element, which may be mounted singly on a mast member or stacked on the mast member with a like antenna, the improvement comprising: a pair of fixed, spaced, connector posts attached to said boom and electrically connected to said driven element; a pair of elongated relatively rigid bars, each bar being secured to a post respectively for pivotal movement about a generally horizontal axis at one end of the bar, the length of said bars from said axis to the other ends of bars being approximately one-half of the stacking distance; and insulator means connected to each of said bars intermediate the ends thereof to releasably support said bars from one of said members.

5. In an antenna including a horizontal boom, a driven element and a parasitic element, which may be mounted singly on a mast or stacked on the mast with a like antenna and connected by a pair of lead wires to radio wave equipment, the improvement comprising: a pair of fixed, spaced, connector posts extending parallel to said boom and to either side of said boom, said posts having extending ends in a plane normal to said boom with the plane being spaced from said driven element, said posts being electrically connected to said driven element; a pair of elongated relatively rigid bars, one end of each of said bars being secured to an extending end of a post respectively for pivotal movement about an axis parallel to said plane; an insulator extending between said bars intermediate the ends thereof; means releasably connecting said insulator to said bars and positioning said bars in planes generally parallel to said boom, said means providing connectors for said lead wires when said antenna is used singly; and means at the other ends of said bars for connecting the bars of one antenna with the respective bars of a second antennawhen the antennas are to be stacked on a mast.

6. In an antenna including a horizontal boom, a driven element and a parasitic element, which may be mounted singly on a mast or stacked on the mast with a like antenna and connected by a pair of lead wires to radio wave equipment, the improvement comprising: a pair of fixed, spaced, connector posts extending parallel to said boom and to either side of said boom, said posts having extending ends in a plane normal to said boom with the plane being spaced from said driven element, said posts being electrically connected to said driven element; a pair of elongated relatively rigid bars, one end of each of said bars being secured to an extending end of a post respectively for pivotal movement about an axis parallel to said plane; an insulator extending between said bars intermediate the ends thereof; means releasably connecting said insulator to said bars and positioning said bars generally parallel to said boom, said means providing connectors for said lead wires when said antenna is used singly; clip means to releasably engage said insulator and said boom, said clip means positioning bars in a generally horizontal plane when engaged; and means at the other ends of said bars for connecting the bars of one antenna with the respective bars of a second antenna when the antennas are to be stacked on a mast.

7. An antenna for connection to a twin transmission line, said antenna comprising a generally horizontal boom having a longitudinal axis, an insulator affixed to said boom with at least a portion of the insulator being spaced vertically with respect to said boom; a driven element having two feed ends, said element extending outwardly at opposite sides of said axis with said ends being attached to said insulator at opposite sides of the axis; a pair of generally horizontal posts aflixed to said insulator at opposite sides of said axis respectively and electrically connected to said ends respectively, said post extending in one direction generally parallel to said axis and having extending ends beyond the adjacent portions of the element in said direction; a first elongated bar having one end pivotally attached to one post adjacent the extending end thereof; a second elongated bar having one end pivotally attached to the other post adjacent the extending end thereof; a second insulator extending between said bars and maintaining said bars substantially parallel; said posts and said bars forming a quarter wave matching transformer; means to releasably engage said second insulator and said boom; and means to connect said transmission line to said bars at a plurality of points along the length of the bars respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,611,086 Amy et al. Sept. 16, 1952 

